The seaside villages of Borth and Ynyslas are built on a coastal landform know as a spit. It has developed naturally over time by the action of the wind and waves moving and depositing beach sands and gravels during storms. The spit has not always been in its current location, it has been pushed progressively westward as sea-level have risen since the end of the last ice-age. Behind and underneath the spit is Cors Fochno (Borth Bog) which is the largest active raised bog in Britain.
Evidence of how the environment of Borth and Ynyslas has changed can be seen in the beach foreshore. Ancient tree stumps and thick blocks of old peat littler the shore illustrating how sea levels have changed. About 5000 years ago much of the area was a pine and oak forest, with the sea much further out into Cardigan Bay. However, after about 1000 years, the local water table began to rise, drowning the trees and stating the formation of Cors Fochno. As sea levels rose, the spit protecting the bog was moved inland coming to rest in its current location.
Peat bogs are a fantastic archive of palaeoenvironmental information, preserving biological, mineralogical and chemical material that can be used to reconstruct past environmental conditions. Cors Fochno has already revealed the natural and man-made changes to the local vegetation, evidence for metal mining during the Bronze Age and Roman Period, volcanic ash from Alaskan and Icelandic volcanoes and the chemical signature of storms during the last thousand years.
It is important to understand the timing and rates of development of coastal features such as spits. They are dynamic, fragile ecosystems in their own right but also affect the wider landscape and habitats within it. Future increases in sea-level coupled with an escalation of storm frequency or intensity may have significant implications for coastal communities and heritage sites.
Why are we working here?
CHERISH is working at Borth and Ynyslas to understand when the spit reached its current location and how long it took to develop through the process known as long-shore drift. We are taking cores from the dunes and beach ridges and dating the sand overlying the peat bog deposits using OSL. We have conducted ground penetrating radar to look beneath the ground surface and combined this with high-resolution ALS data to reconstruct how the course the river Leri has changed through time.